The present invention broadly relates to roll or calendering devices and, more specifically, pertains to a new and improved construction of a calender for pressure and thermal treatment of material webs.
Generally speaking, the present invention relates to a calender for the pressure and thermal treatment of sheets of plastic or of textile, or both, such as fiber webs, and having at least one heated roll and one counter roll cooperating therewith.
In known calenders or calendering devices of this type, the heated rolls are exposed to ambient air without heat insulation which leads to significant losses of energy. These heat losses generally have the advantage, as far as they are uniform, of tending to equalize the temperature profile of the rolls and therefore of providing a uniform quality of the sheet of material or web produced, especially in relation to its width. If these heat losses were prevented, the required uniformity of the temperature profile over the length of the roll would no longer be guaranteed.